Phase-regulating system



- will be repeaters inthese linesvat Patented Sept. ll, 1928.

UNITED STAT-Es PATENT i innings i OFFICE.

PHASELREGULATING SYSTEM.

Application inea umn se, ma serial 1ro. 97,79s. l

It is an object of my invention to' provide apparatus and method for compensating relative phase shift amongvarious carrier current components in a multiplex signal system. Anotherobject of myinvention is to provide compensation 'for phase shifts due to changes in the distributed capacity along af 'and in phase with the transmission line; suclrchanges of capacity may be caused by changesof temperature along the line. Another object of my invention isA to. provide Acompensation for both resistance changes and capacity changes causedl nother object of my inventionis to sideration of anl example ofpractice according to the invent-ion which I have chosen to disclose in this specification. 'It will be un-4 derstood that the following description relates to this particular example of theinvention and that the invention will be. defined in the appended claims.

Referring to the drawings, Figure 1 is a general diagram showing av system with which my invention may be pract'iced; and

Figs. 2 and 3 are curve diagrams that will be referred to in explaining the principlesv l .which is' balanced by the involved in this connection.

which my invention may be employed advantageously, consider a plurality of loaded line circuits extending a long distance and comprised wit-hin onecable. In addition to the loading coils at proper intervals, there reater t intervals. Some of the conductor palrs will bef'fappropriated to respective signaling circuits with S22-type repeaters,r and other conduct-or pairs will be employed in four-wire circuits. Since the circuits are all loaded lines, they will all cuty off at frequencies somewhat above the essential voice freguegncy range. Some of these circuits ofzvoiceffrequency range may be employed forrnultiplex telegraph signaling. In this case, ,various different frequencies throughout the "range these'diierent frequencies will all be superby temlperature changes along a transmission aline.

provide a network system at ,a repeater sta- 'posed in one conductor may NYQUIs'r, or ammonia, NEW JERSEY, assIGNoa'ro enmarcan I .um marasma conm, a coaroaamron or NEW Yoan.

nent currentof a single frequency may be split into two components 90 and signals may be transmitted on each component b phase reversals thereof.. Locall generate `"currents at the receiving end wi be employed, corresponding in frequency various current com- Aponents received on the line. To maintain this correspondence of phase betweenthe received .currents and the locally generatedA currents, it will b'e important to prevent relative phase shifts` from time received currentsl The circuits in the cable will'besubject to temperature changes from time to time, and these-` changes will have two efectson the electrical c aracteristics of any circuit in the cable. crease theresistance ofthe circuit and will also increase the distributed capacity be- `of the circuit. Such phase tween the'conductors changes-will tend toproduce relative apart in phase, p

totime in the Vincrease of temperature vwill inshifts among the component currents of vari-fv ous frequencies. Bymy invention it becomes possible tocompensat'd suchchanges, so that there shall be no substantial change in attenuation nor in relative phase shift of thereceived currents on the circuit referred to.

Referring to Fig. 1, this shows a four-wire circuit on the right consisting of the two conductor pairs 21 and 22; f These are connected through the usual hybrid coill arrangement 23 with the two-wire circuit 24 onthe left,

network 25.

AThese circuits 21, 22 and 24 are all loaded lines comprised with lmany othercirvuitsin a single cable. Also in the same cale is a vcircuit V.comprising another" pair of conductors 26like the ordinary conductors of the cable. At distant points on each-side, perhaps several repeater stationsaway, the ends of the conductors 26 are joined as'at 27 to `form loops.v

The :two loops in parallel form one 'side or arm ofa Wheatstone bridge..`between the yvertices 29 and 30, The opposite side ofthe bridge is the resistance 28-31, and the two -.remaining sides of the bridge are 28-29- and 3138-30. The energy of the battery32 is applied Aacross the twoopposite vert1ces-28 and 30. It will be seenthat the point'30 is a contact arm which is adjustable b the-ro- 'tation of the shaft 4S. The output'bridgin ,1'

33 whose e other to.

the

31 comprises the polarized rela armature 37 shifts one way or t apply positive or negative ,battery to motor 34 that rotates the shaft S. 'This shaft S carries the contact arm 30, as already mentioned, and also a contact arm 35 that engages some one of a row of contact points 36. Y

An increase of temperature on the'line increases the' resistance of the ilot wire cir'- 'cuit 26 and imbalances the bridge. The resulting'current from the battery, 32 in the relay 33 shifts its armature 37 and applies positive or negative battei to the m'otor 34 which rotates the shaft and shifts the Contact 30 in a suitable direction to reestablish the brid e balance, .upon the occurrence of which conition the armature 37 opens its contact and stops the operation of the motor 34. The direction of rotation of the shaft S for an increase of temperature' is clockwise, looking at the contact arms 30 and 35 in Fig. 1.

The four-wire circuit comprising the two conductor pairs 21- and 22 is equipped with the usual one-way repeaters 39 and 40. The re sociate with one air of such repeaters 39 and 40 at a sing e station. The one-way repeater 39 comprises the ampliemof two stages 41 and 42. At the-input of the amrious contact points to the pli er 42 is a potentiometer 43, and connection is made from one or another of its vaid 44,-through the closure' of a correspon ing relay armature 45. The armatures, 4such as 45, are con-- trolled by respective relays such as 46, and the circuit conductors 48 for fthese relays extend respectively therefrom to the respective contact points 36 that have already been mentioned in connection withl the contact arm 35 of the shaft S. The set of relays such as 45 and the conductors 48 are for the particular four-wire circuit 21, 22; branch conductors 47 go to correspondirrg relays for re lating other circuits in the same cable. n tandem in the line 421 is an artificial line 70 comprising series inductances 49 and alternately disposed shunt capacities 501- Each pair of inductance coils'49 on the two sides of the lines has substantially the same inductance value as in a loadcoil on the line, and each shunt condenser 50 has a capacity somewhat less than the shunt capacity of a section of the line between load cils. As?

sociated with each shunt condenser 50 are,

two other condensers 51 and 52, and the capacity of condenser 50 and one-of these two condensers 51 or 52 in parallel across the line is substantially the same 'as the normal shunt capacit of a section of the; line between load coils at an ordinary intermediate temperature, butsthe capacity of Iall three condensers 50, 51 and 52 in parallel is greater'than o f such a line section. As will tacts 53, 54 or 55, 56 rest on the correspond. -ing plate lator now being described is as beJ seen from the drawing, the condenser 50 stands permanently across the line, but each of the condensers 5l and 52 is operatively connected across the line only when its con- 57 or 58 of the controller 59. This cdntroller 59 is on the same shaft S that car ries the contact arms 30 and 35 and is turned by the motor 34. The shaft S carries similar controllers for other circuits in the same cable. l l Associated with line 22 `are a tentiom veter 43', an artificial line 70 an a control ler 59' corresponding respectively to the ele ments 43, 70 and 59 associated with line 21. It has already been pointed out that an increase of temperature along the cable increass the resistance of the pilot wire loops 26' and causes the shaft S to rotate clockwise las view/ed where it carries the contact arms 30 and 35. This same clockwise direction of rotation is indicated by the arrows adjacent to the controllers 59 and 59.

The contacts such as 53, 54, and 56 forthe controller 59 and the corresponding contacts for the controller 59 are assume to be positioned along the horizontal dotted lines 63 and 63 shown across those controllers. The increase of temperature along the cable already referred to and the corres ending increase" of the resistance of thev p' ot wire circuit 26 and the resulting clockwise rotation ofthe shaft S will carry the pair of contacts 60, 61 off the controller plate 62 and thus remove the condenser.52 from'across the line, capacity of the sectional artificial line. Thus it will be seen that the increased capacity across the line 'due to the increase 0L temperature is of capacity in the sectional artificialline.l '1

At the same time the clockwise rotation of the shalft S shifts the contact arm 35 from one point to the next of the series of contact points 36 and takes the current off from one relay 46and puts it on the next relay 46 thus effectively changingthe connection o they 'd 44 to the next lower` point of the potentiometer 43. This puts a higher electromotive force on the grid 44 and gives an in- .creasedover-all amplification factor for the repeater and compensates the v'attenuaticm.

andfphase shift due tothe increasedr resistance on thc linel caused by the increase of tem rature. ..1 T e steps of the potentiometer 43 are shown symboliclly inthe figure, and for liccuracv in maintainingethe phase shift un' properly .design s changedtlrey. will each resistance and reactance networks, and not'il -meresimple resistance's, ,tl iou,.;hv approximate compensation for attenuation may be effected if these potentiomefei' steps are all mere ohm'ic resistnoesand approximate @meeuwen fer Phase shift: can @las be '1 l0 decreasing by so much the shunt compensated by the decrease 1 cured even thouf;1 the only reactance is in the end step of t e otentiometer. Y

An inspection of ig. 1 will show that with increase of temperature' on the line' and clockwise rotation of the shaft S from the position indicated by the dotted line 63 the condensers such as `52 will be cut off successvely from right to left. On the other hand, with decrease of temperature on the line and consequent counterclo'ckwise rotation of the shaft S the condensers such as 51 will be operatively connected in succession from right to left.

As a reasonable example for illustrative purposesyit may be assumed that the capacity across aconductor pair of a cable increases five parts in 10,000 for every degree centigrade rise in temperature. The resultant relative phase shift will be greater in a Y medium heavy loaded cable than in an extra light loaded cable, and the mediunr heavy loaded cable will be assumed for illustrative purposes. Assume /that the circuit in this y cable is being operated for multiplex telegf rapliy on channels given by frequencies from 425-to 2295 cycles per second in `odd multiples of 85,'that is, the channel frequencies ,e

run 425, 595, 765 1275 1955, 2125 and 2295'. Assume further that the current of 'intermediate frequency, 1275 cycles per secat an intermediate temperature all the other frequencies will be in a propriate synchronism. Atthis interme late temperature all' the condensers 51 will .be connected across the artificialline, but the condensei's 52 will be disconnected. Each pair of condensers and 51 has a combined-capacity equal to thel capacity of aline section between load coi s.

As the temperature along the line departs from the assumed intermediate value, there will be a relative phase shift among the coinponent carrier currents on the line, but of-` course the temperature change along the line will not have any effect on the phase re' lations of the locally generated currents atl lthe receiving end. Y

By my invention the relative phase shifts of the currents on the line will be, compensated, so as to keep the received currents in an unchanging phase relation.. j

As to the magnitude of the relative phase shift that may be caused by considerable temperature changes, attention is directed to the curve of Fig. 2. lThis is based on an assumed line of mediumheavy loaded side circuit with 159 load coils. According to the data that have been set .forth earlier in this s ecification, atemperature change of 55 ahrenheit will cause a change of 1.528 r 137. Such changes are seen to be consider-` able and to require compensation.- p

Fig. 3 shows the resultant or residual rela- .tive phase shifts for this assumed example after compensation as com ared with Fig. 2 before compensation. ese iigures'are drawnmo different scales. Whereas the relative phase shift without compensation ma be as much as +143 at frequency 2000, it is only -1.6 with compensation at the same frequent: and: less at all other frequencies within t e'essential voice range. Fig. 3 is computed for 1015 sections of artificial line and with each capacity' reduced to f6 its .normal value,..this normal value being the" line ca acity betweenconsecutive loadsat the norma temperature from whichthe 55 temperature change was reckoned.` A fractional number of sections would not be practicable ico but 10 or 11 .sectionswould give nearly the same result, provided the total capacity change is kept the saine.v

I claim: 1

1. The method of compensatingat a repeater for temperature changes on a transmission line equi ped with re eaters, and with tandem artiiEi in iicreasing'the am liiication ratio as'the temperature rises, an also at the same place decreasing the artificial shuntcapacity asi cial lines, w 'ich'consists" Y the temperature rises, and varying these magnitudes inthe opposite diiiection as the temperature lowers. 'U 2. The method of compensating relative posed to temperature changes, and 4means to compensate for phase shifts due'` to -such changes, said means comprising a potentiometer across the 1ine a tandem` sectional network in the line with shunt capacities,

and automatic means to increase the poten-f 'phase shift due to increase of resistance and j tiometer output and decrease the shunt capacities as the temperature rises, and vice versa.

4. In combination, a transmission, line exposed to temperature changes, a pilot circuit exposed to the same changes, a bridge having this pilot circuit in one arm thereof, zand means controlled by the bridge to compensate for phase shifts due to such. term perature changes, said. means comprcapacities to be cut in or out of paralleV capacity connected to said circuitil means' operated by resistance changes in t el pilot wire to compensate for resistance cha in the circuit, and further means contro ed by said resistance changes to vary the arti- 'ficial shunt capacity in accordance with the resistance changes.

7. In combination, a transmission line exposed to temperature changes, a pilot circuit exposed to the same changes, a repeater anda variable capacity associated with the line, a bridge having the pilot circuit in one arm thereof, and means controlled by the bridge to change the amplification ratio and to vary the associated capacity, both in accordance with the resistance change of the pilot circuit.

In timony whereof, I have si ed my name to this specification this 22u day of March, 1926.

HARRY NYQUIST. 

